If you want to enable this, you need to create a native mobile profile in your navigation.
If you want to create a native app, you can always start from the Blank Native app template from Mendix.
You need to add a Native navigation profile in the application to be able to Build Native Mobile App.
Go to Navigation → Add navigation profile → Choose native mobile → Click ok and then check this option again.
Try following steps
I had the same issue. I was lacking the Mendix Native Mobile Builder dependency. Re-installing Mendix using the online installed did the trick for me.
A bad user experience is one of the main reasons why your app gets rejected from the Apple App Store. One of the main issues with a native app is that it will not be submitted to the App Store if it does not meet their requirements. However, if you want to build an app for iOS and Android, then read on as we walk you through what Native Apps are and who uses them.